Drinking mug



FIG. 1 is a front view, the rear view being a mirror image thereof, of a drinking mug showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a right side view thereof;

FIG. 4 is a left side view thereof; and,

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a drinking mug, as shown and described. 